The heat transfer and friction characteristics of the heat exchangers having sinusoidal wave fins were experimentally investigated. Twenty-nine samples having different waffle heights (1.5 mm and 2.0 m), fin pitches (1.3mm to 1.7mm) and tube rows (one to three) were tested. Focus was given to the effect of the waffle configuration (herringbone or sinusoidal) on the heat transfer and friction characteristics. Results show that the sinusoidal wave geometry provides higher heat transfer coefficients and friction factors than the herringbone wave geometry, and the difference increases as the number of row increases. The i/f ratios of the herringbone wave geometry, however, are larger than those of the sinusoidal wave geometry. Compared to the herringbone wave geometry, the sinusoidal wave geometry yielded a weak row effect, which suggests a superior heat transfer performance at the fully developed flow region. Possible explanation is provided considering the flow characteristics in wavy channels. Within the present geometric range, the effect of the waffle height on the heat transfer coefficient was not prominent. The effect of the fin pitch was also negligible. Existing correlations highly overpredicted both the heat transfer coefficients and friction factors. A new correlation was developed using the present data.