Inorganic fibers form part of the complex mixture of environmental pollutants in Mexico City and in general locations. Upon entering the lungs, some of those fibers are transformed into ferruginous bodies (FB) that can be used as biological markers of exposure to fibers. Hence, the objectives of this study were, first, to describe the most frequent types of FB found in the lungs, and second, to determine the elemental composition of the cores of some of those FB. A total of 264 lung samples collected from autopsies performed at the National Institutes of Health in Mexico City were analyzed. The FB were obtained by digesting the samples in commercial bleach and all the FB were then collected in 0.45 µm Millipore membranes. All the FB obtained from each case were counted directly under bright field microscopy, and then classified by morphology. Results showed from 14.5 FB/g in Category 1 (housewives), to 50.2 FB/g for samples from Category 5 (construction workers), and 152 FB/g for Category 6 (miners). Significant differences were found upon comparing samples from Categories 5/6 to Category 1 (p < 0.05). Type 1 FB were the most frequent ones seen in the samples from Categories 1 to 5. Elemental analyses of the cores of several FB found aluminosilicates, fiberglass, tremolite and amosite asbestos among others. In conclusion, residents of Mexico show exposures to a variety of fibers that induce FB including asbestos.