Sub Command1_Click ()
 Dim myfile, mytext
myfile = "C:\mydatfil.txt"
Open myfile For Input As #1
Input #1, mytext
Text1 = mytext
End Sub

You're not reading the whole file - just the first line

You need to loop through the file adding each new line to the end of your
textbox until you hit the end of the file

Here's one way:

Sub Command1_Click ()
Dim myfile, mytext
myfile = "C:\mydatfil.txt"
Open myfile For Input As #1

Do While Not EOF(1)
  Input #1, mytext
  Text1 = Text1 & mytext & vbCrLf
Loop

'You should always close any files you have opened
'as soon as you have finished with them

Close #1

End Sub

Dim myfile, mytext
myfile = "C:\netlog.txt"
Open myfile For Input As #1
While Not EOF(1)
Line Input #1, mytext
Text1.Text = Text1.Text + mytext
Wend

There are far more efficient ways of getting an entire text file into a Text Box, but I'm not sure what functions VB3 has. If VB3 allows you to use the Get function then you can get the entire file in one go. Have a look.

Mike

(dredging out the VB3 memories, but here goes...)

Avoid using the Input Statement if you can - it does lots
of "useful", if sometimes strange, things on your behalf.

Try the Line Input Statement if you want to read the file
line-by-line or, as in this case, grab the whole lot in one go,
using

Text1.Text = Input$( LOF( iFile ), #iFile )

HTH,
    Phill  W.

. . .