The use of alternative therapies is thought to be common among cancer patients. To clarify the popularity of micronutrients among children with cancer, we performed a controlled follow-up survey. The use of micronutrients and alternative drugs by 15 families of children with acute lymphoblastic leukemia (ALL) receiving chemotherapy (62 members) and 26 control families (106 members) was monitored by means of daily diaries from November 1987 to December 1989. Forty percent of children with ALL (6 of 15) and 7.7% of their controls (2 of 26) took alternative medicines, the usage among the children with ALL being statistically significantly more common (difference, 32.3%; 95% confidence interval for difference [CI] 7.1, 57.5%; P < 0.04). All children with ALL and 50.0% of the control children (13 of 26) took vitamins (difference, 50.0%; 95% CI, 20.4-79.6%; P < 0.01). A total of 27.7% of the other members of the ALL families (13 of 47) and 11.1% of their counterparts in the control families (10 of 90) took alternative medicines, the usage in the index families being statistically significantly more common (difference, 16.6%; 95% CI, 3.4-29.7%; P < 0.03). The malignancy increased the use of alternative medicines among all members of the family and of vitamins and trace elements among the affected children.