RESUMO.-[Índice cardiotorácico e vertebral heart size (VHS) para a padronização do tamanho cardíaco do macaco-prego (Cebus apella Linnaeus, 1758) em imagens radiográficas computadorizadas.] Para a avaliação do VHS e ICT foram utilizadas radiografias toráci-cas computadorizadas de 10 macacos-prego (05 machos e 05 fêmeas) clinicamente saudáveis, oriundos do Centro de Triagem de Animais Silvestres de São Luís-MA-CETAS. Foram tomadas radiografias em projeções laterolaterais e dorsoventrais, para cálculo do Vertebral Heart Scale (VHS) e Índice Cardiotorácico (ICT). O VHS evidenciou valores médios de 9,34±0,32v (machos) e 9,16±0,34v (fê-meas), não ocorrendo diferença estatística entre machos e fêmeas (p>0,05). O ICT evidenciou valores médios de 0,55±0,04 (machos) e de 0,52±0,03 (fêmeas), não sendo verificada diferença estatística entre sexos (p>0,05). Verificou-se correlação positiva entre VHS e ICT (r=0,78). Os diâmetros torácico e cardíaco demonstraram valores médios de 5,70±0,48cm e 3,16±0,40cm nos machos, The VHS and CTR were assessed using computerized thoracic radiographs of ten clinically healthy tufted capuchin monkeys (five males and five females) from the Wild Animal Screening Center in São Luís (Centro de Triagem de Animais Silvestres de São Luís-MA--CETAS). Radiographs were taken in laterolateral and dorsoventral projections to calculate the cardiothoracic ratio (VHS) and vertebral heart size (CTR). The VHS showed mean values of 9.34±0.32v (males) and 9.16±0.34v (females) and there was no statistical difference between males and females (p>0.05). The CTR showed mean values of 0.55±0.04 (males) and 0.52±0.03 (females) and there was no statistical difference between the sexes (p>0.05). There was positive correlation between VHS and CTR (r=0.78). The thoracic and heart diameters showed mean values of 5.70±0.48cm and 2.16±0.40cm in the males, respectively. In the females they measured 5.32±0.39cm and 2.94±0.32cm. There was no statistical difference between the sexes. Our results show that the high correlation found between VHS and CTR permitted the verification with similar clinical precision between the two methods to estimate alterations in the heart silhouette by radiographic examination of tufted capuchin, making it an easy technique to apply that can be considered in the investigation of heart problems for this wild species.