The present study aimed to: (i) define thick melanomas related to nodular melanomas and other melanoma subgroups; and (ii) establish diagnostic delay in relation to the biological behavior of these melanomas and prevention programs. Cutaneous primary melanomas were studied. Nodular melanoma (NM), lentigo maligna melanoma (LMM) and superficial spreading melanoma (SSM) were selected. A further category named vertical growth melanoma (VGM) was also utilized. Analysis for sex, age, different values of thickness (1-2 mm, > 2 mm; 1-3 mm, > 3 mm; > 4 mm), delay to diagnosis and patterns of detection were performed in all of the different subtypes. Eighty-seven patients with melanomas more than 1 mm of Breslow's thickness out of 506 melanoma were collected. Twenty-six were nodular cases, 39 SSM, five LMM and 17 VGM. Of those patients with NM, 42% had a thickness of more than 1-2 mm, 34% of 2-4 mm, 23% of more than 4 mm; and 54% with 1-3, 46% with more than 3 mm; and 58% with more than 2 mm. Even considering different values of thickness of more than 1 mm, a delay to diagnosis was significantly lower in NM (4.79 months) than in other subgroups. The value of more than 1 mm of Breslow's thickness may be sufficient to consider a melanoma to be thick. The lower diagnostic delay of NM suggests that they represent faster growing lesions probably with a different biological behavior than other melanoma subtypes. VGM should not be confused with NM, having a longer delay and different clinical features compared with the latter. They represent an area of diagnostic carelessness than potentially be improved.