Objective: Muscle cramps, sleep disorders, and irritability due to Mg deficiency; and sleep and behavioral disorders associated with Zn deficiency and being cofactors in the melatonin synthesis have suggested that plasma Mg and Zn may be in lower levels in colicky infants. This study aimed to compare plasma Mg and Zn levels of colicky infants and the mothers with controls. Material and Methods: Fifty infants diagnosed with infantile colic and 22 controls aged 1-3 months with their mothers were included in this cross-sectional study. Colic group was divided into two subgroups; Firts infants who were given Mg-containing herbals (herbals-group, n=12) and second infants who were not given any Mg or Zn-containing supplement (study group, n=27). Plasma Mg and Zn levels were measured by Atomic Absorption Spectrophotometer on flame photometry. Results: Mg levels (mg/dl) of the infants were not different between study group (2.46±0.27) and controls (2.37±0.25) (p=0.70). However, plasma Mg levels were higher in the herbals-group (2.68±1.90) than the study group (2.46±0.27) and controls (2.37±0.25) (p=0.04, p=0,004; respectively). Zn levels (mg/dl) of the infants and Mg and Zn levels of the mothers were not different between the groups (p=0.36, p=0.61, p=0.22; respectively). In the herbals-group, four parents reported that the Mg-containing herbals were useful, but Mg levels of their infants were found similar with the infants whose parents reported that Mg-containing herbals were not useful (p=0.79). Conclusion: Plasma Mg and Zn levels of colicky infants and their mothers were not different from healthy controls in this study. Further studies are needed to determine the effect of Mg supplementation on colic severity.