BACKGROUND: Malignant tumours in adolescents and young adults (AYA) are referred to as early-onset cancers. This study analysed the histopathological profile of malignant solid tumours in AYA. METHODS: Records of patients who had confirmed malignant solid tumours were retrieved. Data collected included the treating hospital, year of presentation, age and histological diagnosis. The commonly diagnosed malignant tumours in AYA were compared with tumours in older adults. A p-value below 0.05 was considered significant. RESULTS: A total of 61 828 records were retrieved and 29 974 were excluded. Additionally, 10 55 post-excision results from AYA were excluded. Of the remaining 30 799 records, 13.1% (4 032/30 799) were diagnosed in AYA, of which 18.2% (734/4 032) were in-situ lesions. Overall, 11% (3 298/30 065) of invasive tumours were from the AYA. The majority, 81.1% (3 269/4 032), of invasive and non-invasive malignant tumours in AYA were from females. Breast and cervical cancer constituted 29.2% (962/3 298) and 23.2% (766/3 298) of diagnosed cancers in AYA, respectively. Ten (0.3%) cases of prostate and 0.4% (12/3 298) of lung cancers were reported in AYA. CONCLUSION: Eleven per cent of invasive malignancies were diagnosed in AYA and 81% involved females. Cancers of the breast, cervix, skin, and colon were the top four most common tumours in AYA. The burden of breast and colorectal cancer was higher in AYA than in older adults. Prostate cancer is rare in AYA and lung cancer was not among the top 10 malignant tumours in our setting. Over 11% of primary malignant tumours of the anus, breast, cervix, colon, conjunctiva, liver and rectum were diagnosed in AYA.