Two important unsolved questions related to peripheral parenteral nutrition are the ratio of components in the intravenous (IV) solution and catheter-related complications. The present study was undertaken to evaluate the nutritional profiles of three kinds of IV solutions with different ratios of components, while maintaining the total energy at about 1 200 kcal/day and the amino acid level at 60 g. The IV solution formulas used were as follows : glucose/fat = 2:1, osmolarity ratio = 3.3 for group A, glucose/fat = 1:1, osmolarity ratio = 3.1 for group B, and glucose/fat = 1:2, osmolarity ratio = 2.6 for group C. The incidence and severity of complications were then analyzed in relation to the type of IV solution used, the indwelling time, and the type of catheter (midline catheter or short peripheral catheter). The results of peripheral parenteral nutrition were favorable when the glucose/fat ratio of the IV solution was either 1:1 or 1:2. The midline catheter was inserted for an average of 11.9 +/- 4.0 days, and the incidence of catheter-related complications following parenteral nutrition with a midline catheter was low when the osmolarity ratio of the IV solution was 3.1 or less. These results indicate that a midline catheter is useful when administering peripheral parenteral nutrition.