Possible associations of incidence of non-Hodgkin's lymphoma (NHL) with solar UVR have been suggested (Cartwright e.a. 1994, etc.). Also, incidence for both malignant melanoma of the skin (SMM) and NHL has shown a rapid increase over the last 10-15 years worldwide. On the other hand, cyclicity in variations of incidence rates for SMM was reported (Houghton e.a. 1981, Dimitrov 1998, etc.). The present study analysed trends and variations in incidence of SMM and NHL for the USA. Annual age-standardized incidence rates for SMM and NHL (SEER database, 1973-1989) were compared. Linear and non-linear regression modeling, periodogram regression analysis and parametric tests were applied (Dimitrov e.a. 1995). The analysis denoted non-linear trends of increasing incidence for both SMM and NHL. Cyclic variations in incidence rates for SMM in US females were reported previously (Dimitrov 1993) and now were confirmed also for other strata of the population (mainly, cycles with a period T = 8 divided by 9 years, p < 0.05) as well as revealed for NHL (mainly, cycles with a period T = 8 divided by 9 years). This cyclicity was significant at 95% only for black US males (Table 1). After decycling for hypercyclicity of 20-35 years (long-term cyclic trends), however, significant high-frequency infrannual variations of 3 divided by 5 years appeared in NHL (latter cyclic variations, for instance, were observed in the sunspots index, solar UVR and stratospheric ozone). Also, significant cycles of 11-13 years appeared for white US males. Similar cyclicity of 9 divided by 11 years was observed in sunspots number over the same interval. Trends of NHL were very similar to that of SMM, as were the variations. This study might be considered a contribution to the hypothesis on possible associations of incidence for NHL with heliogeophysical phenomena.