Apoptosis is a universal cellular defense mechanism against viral infection. Curcumin, an anti-inflammatory phytochemical, induces apoptosis through mitochondrial and receptor-mediated pathways, as well as activation of caspase cascades. Here, we investigated the impact of supplementation with curcumin on the expression of a panel of apoptosis- and cytotoxicity-related genes in patients suffering from HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), a progressive demyelinating neuroinflammatory disease caused by HTLV-1 infection. Twenty-one HAM/TSP patients enrolled in this study. Curcumin nanomicelles (80mg/day, orally) were administered once a day for 12 weeks. The mRNA levels of total Fas (tFas), membrane-bound Fas (mFas), Fas-Ligand (FasL), TNF-related apoptosis-inducing ligand (TRAIL), perforin, granzyme A, granzyme B and granulysin were analyzed before and after treatment in peripheral blood lymphocytes. Protein levels of Fas, FasL, TRAIL and granulysin were also measured in serum using ELISA. Curcumin supplementation inhibited FasL mRNA production and up-regulated the expression of pro-apoptotic molecules granzyme A (at the mRNA level) and granulysin (at the protein level), suggesting degranulation of granulysin-bearing cells following curcumin supplementation. Conversely, Curcumin did not affect Fas, TRAIL, perforin, granzyme B at the mRNA level, and anti-apoptotic molecules sFas, sFasL and sTRAIL at the protein level. The present results suggest that curcumin supplementation increases cytotoxicity-related molecules granzyme A and granulysin in patients with HAM/TSP.